Not quite - it shows that it's already in there and just waiting for 9 to mature enough for a release.

We already know that's the case though. The opening poster (who I was originally replying to) even stated this and it was also mentioned in the article.

The point was it's not in the STABLE branch now.

As of right now, it's quite stable - there are people using it in not-entirely-critical production, including me. (I've got a ZFS mirror with dedup and compression on a lab fileserver. It's just for working copies, but I honestly trust it more than how we store the reference copies.)

That's reassuring to hear.

I was adamant I wouldn't bother upgrading my FreeBSD NAS (Not FreeNAS - it's something I built myself) OS as it's running smoothly and - aside the ZFS array - all the other server services are running in VMs (which are kept up to date) hosted on the NAS.

However I might dd a backup image and attempt the upgrade after hearing of your success